Many fluid systems include one or more fluid accumulators. A fluid accumulator may provide, for example, load topping when fluid power demand exceeds fluid supply or regulating system capabilities, and/or may maintain suitable fluid pressure in the event of a momentary fluid power drop-out, and/or may reduce pressure ripple, and/or provides damping for pressure transients and water hammer.
Fluid accumulators come in a variety of styles, depending upon the element that separates the working fluid, such as hydraulic fluid, from a pressurizing fluid, such as a gas. For example, the accumulator styles include bellows style, bladder style, diaphragm style, and piston style accumulators. Some accumulator styles are heavier than others, some are more expensive than others, and some are limited in size. One advantage of the piston style accumulator is that it is relatively lightweight and inexpensive, and spans a relatively large pressure range.
Unfortunately, the piston style accumulator also exhibits a drawback. The drawback is that it can exhibit gas-to-fluid leakage across the piston seal when the working fluid is expended and gas pressure remains. As may be appreciated, gas in the working fluid is typically undesirable.
Hence, there is a need for a piston style accumulator that does not exhibit gas-to-fluid leakage across the piston seal when the working fluid is expended and gas pressure remains. The present invention addresses at least this need.